Jeffrey Lewis, an arms control expert and a scholar at the Middlebury Institute of International Studies at Monterey, has written a terrifying war game scenario for the Washington Post in which he shows how one particularly ill-timed and ill-tempered tweet from President Donald Trump could set off a chain of events that would end in a nuclear war with North Korea.

In Lewis’ scenario, the trouble begins when North Korea shoots down a commercial South Korean aircraft that had strayed into North Korean airspace that it mistook for an American bomber.

In response to this, South Korea orders a limited missile strike against North Korea’s air defense battery to send a message aimed at deterring further attacks from Pyongyang.

Things quickly go haywire, however, Trump sends out an all-caps tweet in the wake of Seoul’s retaliatory strike that reads, “LITTLE ROCKET MAN WON’T BE AROUND MUCH LONGER!”

This leads the North to believe that Trump is planning an imminent invasion — and at that point, Pyongyang unloads its full nuclear arsenal at targets in Seoul, Tokyo, San Diego, Manhattan and, yes, Trump’s Mar-a-Lago resort in Florida.

It would be years before the U.S. government could provide an accounting of the toll,” writes Lewis in his conclusion. “The Pentagon would make almost no effort to tally the enormous numbers of civilians killed in North Korea by the massive conventional air campaign. But in the end, officials concluded, nearly 2 million Americans, South Koreans and Japanese had died in the completely avoidable nuclear war of 2019.”